MODOK should be villain in Ant-Man. Cap has plenty of villains to use, the Ant doesn't.

Plus, it sounds like IM3 might be planting the seeds for MODOK to show up; so if the theory of IM3 and WS taking place at the same time is true, then Big Head wouldn't be around in Cap 2.

Why do you say that? MODOK could have been created by AIM even before the events of IM3 (or even years ago, for that matter). And it's a long shot in the dark right now, but if my Zola-becomes-MODOK theory gets anywhere close to the target, then Zola/MODOK might have been around even during the Cold War era.